1. Field of the Invention
The present invention relates to arrowheads, used in connection with arrows, for the sport of archery or for hunting. More particularly, the present invention relates to a mechanically expandable broadhead having a single fixed, deflection-resistant spear-point blade at the tip thereof, in combination with multiple pivotally movable blades.
2. Description of the Background Art
People in the field of archery or bow hunting commonly use arrowheads for:                (1) preserving the integrity of an arrow; (2) maintaining an accurate arrow flight pattern; and (3) creating a more effective means of harvesting game.        
In the past, to maintain the integrity of an arrow, some type of metal has been provided at the arrow tip. Metals used for arrowhead manufacture include stainless steel and steel alloys. Titanium is also becoming fairly common in arrow tip manufacture.
While almost any metal arrowhead would suffice to preserve an arrow's structural integrity, one objective, among arrowhead makers, is to create an arrowhead that both maintains an accurate flight pattern, and maximizes the effectiveness of a strike, to allow the bow-hunting enthusiast to efficiently harvest game. An arrowhead with relatively small blades provides accurate arrow flight, but offers a less effective or efficient means of harvesting game. In contrast, an arrowhead with large blades gives the arrow a less effective flight pattern, but provides for a more effective strike and harvest.
Today, selected hunters and some archery enthusiasts use mechanically expandable broadhead-type arrowheads. The expandable blade arrowhead offers a combination of both accurate arrow flight and effective harvest ability, in a single arrowhead. Expandable blade arrowheads tend to be accurate during flight, since the arrowhead remains small in diameter. Upon contact with the target or game, the arrowhead expands in diameter as large blades spring open, creating a larger area of penetration, and consequently, a more effective harvest. In this type of arrowhead, expansion of the blades, from a stored position to a fully deployed position, is caused by the mechanical action of the arrowhead striking the target.
Several inventors have independently patented different designs for mechanically expandable arrowheads.
U.S. Pat. No. 4,940,246 to Stagg (1990) discloses a mechanically expandable arrow attachment and/or arrowhead in which two actuator members protrude from opposite sides of a cylindrical central body. When the arrowhead of Stagg strikes a target, the actuator members open integrally attached cutting blades, which are initially folded into the central body. During deployment of the cutting blades, the actuator members move through the cylindrical body and emerge on the opposite side.
While the Stagg reference discloses the combination of a fixed arrow tip with mechanically expandable blades, the actuator members of Stagg are spaced significantly away from the fixed tip, requiring significant entry depth of the fixed tip into a target before the mechanical blades begin to expand. In addition, in the design of Stagg, the actuator members are located relatively close to the pivot point, providing a relatively small lever arm to pivotally move the blade.
U.S. Pat. No. 5,178,398 to Eddy (1993) discloses another use of expandable blades. A rubber band is positioned over two expandable blades, to keep the blades closed during an arrow's flight. The band's position also prohibits the opening of the blades until the arrowhead penetrates its target, as the blades must break the band to expand.
U.S. Pat. No. 5,803,848 to Anderson (1998) uses a tip-actuated method of deploying two retractable blades. However, in typical hunting conditions it is possible that debris could collect in the actuator lip of the arrowhead of this design, limiting the effectiveness of the arrow.
U.S. Pat. No. 6,015,357 to Rizza (2000) contains two opposed blades that can either remain stationary or become expandable, depending on the consumer's desired use.
Several arrowhead patents have been issued with expandable blades retained by an annular member, such as an O-ring or rubber band, during flight. U.S. Pat. No. 5,322,297 to Smith (1994), U.S. Pat. No. 5,564,713 to Mizek et al. (1996) and U.S. Pat. No. 5,879,252 to Johnson (1999) all contain expandable blades retained by an annular member; however, none of these arrowheads contain a fixed-in-place blade, to ensure that the arrowhead retains some level of effectiveness, in the event that the expandable blades fail to deploy.
U.S. Pat. No. 6,554,727 to Armstrong et al. discloses another expandable blade arrowhead.
It has been discovered that if the known expandable blade arrowheads do not hit directly on a solid target area, or if they strike a target at an angle, these arrows may become deflected rather than entering into the target. Expandable blade arrowheads have been known to “bounce off” or ricochet away from the target in some instances. In addition, expandable arrowheads of the known type may have a greater tendency to bounce off than standard arrows, because of the requirement of the target causing the blades to open mechanically.
While the known arrowheads have some utility for their intended purposes, a need remains for improvement in the arrowhead art. A need exists for an arrowhead having multiple parallel expandable blades, in which actuators for the expandable blades are situated close to a fixed blade at the tip of the arrowhead, in order to minimize the time between entry of the fixed blade and the beginning of deployment of the expandable blades.